Blade anchor systems for bone fusion

ABSTRACT

Fusion devices include blade anchors. The blade anchors may slidingly penetrate a bone or bone fragment, and may induce compression of one bone to another or one fragment to another. The fusion devices may also include a body to which the blade anchors connect.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional of:

U.S. Provisional Patent Application No. 61/554,386, filed Nov. 1, 2011and entitled BLADE ANCHOR SYSTEMS FOR BONE FUSION.

The above-identified document is herein incorporated by reference in itsentirety.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates to embodiments of blade anchor fusiondevices that may be used to fuse the carpal bones, such as the hamate,lunate, capitate and triquetrum. It will be appreciated that any of thedisclosed embodiments may have application outside of carpal bone fusionapplications, and may be used to provide compression across a fusion orfracture line in any application where a typical fusion device or bonestaple may be used. It will also be appreciated that any of the belownamed embodiments can be mixed and matched to form alternateembodiments.

An example of the present technology is concerned with fusion of thecarpal bones by blade anchors that extend outward from a central body.The blade anchors may be secured to the body by a proximal threaded cap.

Those of skill in the art will recognize that the following descriptionis merely illustrative of the principles of the disclosure, which may beapplied in various ways to provide many different alternativeembodiments and may be applicable outside the fields of surgery ormedical devices. While the present disclosure is made in the context offusing the carpal bones in the wrist for the purposes of illustratingthe concepts of the design, it is contemplated that the present designand/or variations thereof may be suited to other uses, such as fusingthe tarsal bones of the foot, or other joints in the human body, or tostabilize bone fractures, etc. Moreover, the implants, instrumentationand methods set forth herein may be used in open, percutaneous, and/orminimally invasive procedures.

All changes which come within the meaning and range of equivalency ofthe claims are to be embraced within their scope.

Standard medical planes of reference and descriptive terminology areemployed in this specification. A sagittal plane divides a body intoright and left portions. A mid-sagittal plane divides the body intoequal right and left halves. A coronal plane divides a body intoanterior and posterior portions. A transverse plane divides a body intosuperior and inferior portions. Anterior means toward the front of thebody. Posterior means toward the back of the body. Superior means towardthe head. Inferior means toward the feet. Medial means toward themidline of the body. Lateral means away from the midline of the body.Axial means toward a central axis of the body. Abaxial means away from acentral axis of the body. Ipsilateral means on the same side of thebody. Contralateral means on the opposite side of the body. Thesedescriptive terms may be applied to an animate or inanimate body.

SUMMARY

In an aspect of the technology, a fusion device includes a body with afirst end, a second end opposite the first end, and a plurality ofundercut slots extending between the first and second ends; and at leastone anchor with a protrusion, an arm, and a blade, the protrusionengaging a correspondingly shaped one of the plurality of undercutslots, the arm extending outward from the body and terminating in theblade, the blade extending transverse to the arm.

In an embodiment, the first and second ends are planar, and the bodyincludes a cylinder extending between the first and second ends.

In another embodiment, the protrusion is axially movable along thecorrespondingly shaped one of the plurality of undercut slots.

In yet another embodiment, a second anchor includes a second protrusion,and the second anchor engages a second correspondingly shaped one of theplurality of undercut slots.

In yet another embodiment, the second anchor includes a second arm,wherein the second arm is longer than the first arm.

In yet another embodiment, the device includes a cap threadedlyconnected to the first end of the body.

In yet another embodiment, the anchor includes a tapered portionadjacent to the second end of the body.

In another aspect of the technology, a fusion device includes a firstcomponent with a first body, a first arm, a first blade, and aprotruding connecting feature, wherein the first arm extends outwardfrom the first body and terminates in the first blade, wherein the firstblade extends transverse to the first arm, wherein the protrudingconnecting feature protrudes from the first body; and a second componentincluding a second body, a second arm, a second blade, and a receptacle,wherein the second arm extends outward from the second body andterminates in the second blade, wherein the second blade extendstransverse to the second arm, wherein the receptacle is recessed withinthe second body; wherein the first and second components are coupledtogether, the protruding connecting feature is received in thereceptacle, and the first and second bodies are aligned.

In an embodiment, the first blade has a first leading point and a firsttrailing portion, wherein the second blade has a second leading pointand a second trailing portion, wherein the first and second leadingpoints diverge outward from the first body, wherein the first and secondtrailing portions converge toward the first body.

In another embodiment, the second arm is longer than the first arm.

In yet another embodiment, the protruding connection feature has prongsextending longitudinally from the first body.

In yet another embodiment, the second component rotates relative to thefirst component.

In yet another embodiment, the protruding connecting feature rotateswithin the receptacle.

In yet another aspect of the technology, a fusion device has a centralportion with a sharpened biconcave leading edge, a blunt trailing end, afirst lateral end and a second lateral end opposite the first lateralend; a first lateral blade transversely mounted to the first lateral endof the central portion; and a second lateral blade transversely mountedto the second lateral end of the central portion.

In an embodiment, the blunt trailing end is concave.

In another embodiment, the first lateral blade has serrations.

In yet another embodiment, the first lateral blade has a first exteriorsurface and a first interior surface opposite the first exteriorsurface, wherein the first exterior surface faces away from the centralportion, wherein the first interior surface is sloped and intersects thefirst exterior surface at a first tip portion.

In yet another embodiment, the second lateral blade has a secondexterior surface and a second interior surface opposite the secondexterior surface, wherein the second exterior surface faces away fromthe central portion, wherein the second interior surface is sloped andintersects the second exterior surface at a second tip portion.

In yet another embodiment, the first and second tip portions divergeoutwardly from the central portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure will now be discussed withreference to the appended drawings. It will be appreciated that thesedrawings depict only typical examples of the present disclosure and aretherefore not to be considered limiting of its scope.

FIG. 1 is a front oblique view of a fusion device;

FIG. 2 is an oblique view of the fusion device of FIG. 1 implanted amongcarpal bones of a wrist;

FIG. 3 is a front oblique view of another fusion device;

FIG. 4 is a front oblique view of a component of the fusion device ofFIG. 3;

FIG. 5 is a front view of the component of FIG. 4;

FIG. 6 is a front oblique view of another component of the fusion deviceof FIG. 3;

FIG. 7 is a front view of the component of FIG. 6;

FIG. 8 is a front oblique view of yet another fusion device; and

FIG. 9 is a front view of the fusion device of FIG. 8.

DETAILED DESCRIPTION

While certain embodiments are shown and described in detail below by wayof illustration only, it will be clear to the person skilled in the artupon reading and understanding this disclosure that changes,modifications, and variations may be made and remain within the scope ofthe technology described herein. Furthermore, while various features aregrouped together in the embodiments for the purpose of streamlining thedisclosure, it is appreciated that features from different embodimentsmay be combined to form additional embodiments which are allcontemplated within the scope of the disclosed technology.

Not every feature of each embodiment is labeled in every figure in whichthat embodiment appears, in order to keep the figures clear. Similarreference numbers (for example, those that are identical except for thefirst numeral) may be used to indicate similar features in differentembodiments.

Any of the devices described herein may be fabricated from metals,alloys, polymers, plastics, ceramics, glasses, composite materials, orcombinations thereof, including but not limited to: PEEK (polyetherether ketone), commercially pure titanium, titanium alloys, ASTM F67,Nitinol, cobalt chrome, cobalt chrome alloys, stainless steel, UHMWPE(ultra-high molecular-weight polyethylene) and biodegradable materials,among others. Different materials may be used within a single part. Theimplants disclosed herein may also encompass a variety of surfacetreatments or additives to encourage bony attachment, including but notlimited to: porous coatings, hydroxyapatite, tricalcium phosphate (TCP),anti-microbial additives, analgesics, anti-inflammatories, bonemorphogenic proteins (BMPs), phorbol myristate acetate (PMA), bonegrowth promoting material, poly-L-lactide (PLLA), polyglycolide (PGA),tricalcium phosphate (TCP), demineralized bone, cancellous bone chips,etc. Any implant disclosed herein may include a radiographic marker forimaging purposes. Any implant disclosed herein may be colored, coded orotherwise marked to make it easier for the surgeon to identify the typeand size of the implant.

FIGS. 1-2 illustrate a fusion device that may be used to fuse a set ofcarpal bones, specifically the hamate, lunate, capitate and triquetrum.The fusion device includes a body and a plurality of anchors that extendradially from the body.

As seen best in FIG. 1, fusion device 100 includes a body 102, which maybe cylindrical and may include a proximal first end 106 and a distalsecond end 110. The body 102 may also be polygonal, oval, elliptical,asymmetric, or irregular in cross section instead of circular, as for acylindrical body. The body 102 may be smooth, or may be externallytextured, for example, threaded, ridged, or studded. The body 102 mayinclude a plurality of undercut slots 108, channels, or grooves alongthe surface that may extend between the first end 106 and the second end110. The slots, channels, or grooves may act as connecting features forone or more bone anchors. Dovetail, T, or cylindrical protrusions on theanchors may engage correspondingly shaped slots 108, channels, orgrooves in the body. In the example of FIGS. 1-2, the body 102 includesfour grooves 108 and four anchors 104. The body 102 may be centrally,eccentrically, symmetrically, or asymmetrically located among theanchors 104. The grooves 108 may remain stationary along the surface ofthe body 102, or may be allowed to rotate around the axis of the body102 to be better placed for blade anchor insertion. For example, thegrooves 108 may be allowed to rotate about a central longitudinal axisof the body 102.

The anchors 104 may include an outward face 112 that includes blades114, fins, barbs, teeth or other features to drive the fusion device 100into the carpal bones. The blade anchors 104 may include a taperedportion 116. The anchors 104 may share some or all of thecharacteristics of the bone anchors disclosed in U.S. patent applicationSer. No. 12/640,892, which is incorporated herein in its entirety.

When fusion device 100 is assembled, the blade anchors 104 may be atleast partially contained within the grooves 108 and may extend radiallyoutward from the body 102. The blade anchors 104 may be axially moveablealong the grooves 108 to be driven into the carpal bones. The bladeanchors 104 may be variably offset from the body 102 to accommodatevarious patient anatomies. Additionally, to accommodate various patientanatomies, multiple bodies 102 may be placed adjacent to one another,creating, for example, a figure-eight configuration. The multiple bodiesmay be formed integrally with each other, or may be modularlyconnectable by fitting a projection on a second body into a groove on afirst body.

The end 106 of body 102 may also include a proximal threaded portion(not shown) to connect to a threaded cap 120 that may be placed onto thefirst end 106 body 102 after blade anchor insertion. The cap 120 may beaxially aligned to the body 102 to lock the blade anchors 104 in placeas well as provide a smooth articulation with dorsal tendons. The cap120 may include generous edge breaks to soften exterior edges withfillets or chamfers. The cap 120 may also be polished to further smoothsurfaces which face or contact soft tissues.

FIG. 2 provides a proximal view of fusion device 100 embedded into thewrist joints to fuse the four carpal bones: hamate 92, lunate 94,capitate 96, and triquetrum 98. The device proximal threaded cap 120 canbe seen to be nearly continuous with the surface of the bones.

Fusion device 100 may also include additional cut-outs or fenestrations(not shown) for osseus ongrowth/ingrowth means. The fusion device 100may be filled with biologics for osteoinduction and osteoconduction, thebiologics accessible to the host tissues through the cut-outs orfenestrations. The fenestrations may be located in the body, forinstance between the grooves 108, or in the end 110. Fenestrations mayalso be located in the cap 120 in some examples.

FIGS. 3-7 illustrate another example of a fusion device that includes aplurality of blade anchors and a minimalistic body. The blade anchorsmay provide compression across a fusion or fracture line in anyapplication where a typical bone staple could be used, such as in smallbone osteosynthesis or sternal closure.

Fusion device 200 may include at least two components, or staples, thatare connected via a central mechanism, allowing fragments to becompressed towards a single point or axis. Fusion device 200 includes afirst component 202, and a second component 204.

Referring to FIGS. 4-5, the first component 202 includes a body 205, afirst arm 206 that terminates in a first blade 208, and a second arm 210that terminates in a second blade 212, the second arm 210 opposite thefirst arm 206.

The first blade 208 may be oriented perpendicular to the length of thefirst arm 206 in two planes and the second blade 212 may be orientedperpendicular to the length of the second arm 210 in three planes, andthe arms 206, 210 may be mutually parallel and collinear. Thisorthogonal arrangement is one example of the contemplated range of allangles between the arms and blades. Other examples include blades whosetips diverge or converge, a blade forming an acute angle with an arm inone or more planes, or arms forming an included obtuse or acute anglebetween them in one or more planes. The length of the first arm 206 andthe second arm 210 may be variable to accommodate different patientanatomies and different applications. For example, the first and secondarms 206, 210 may have equal or unequal lengths. A set of firstcomponents having a range of arm lengths may be provided. The firstcomponent also includes a central portion 214, located between the firstarm 206 and the second arm 210. The first and second arms 206, 210 maybe said to extend radially from the central portion 214. The first andsecond arms 206, 210 may have concave leading edges 230 and blunttrailing ends 232. Together, the first and second arms 206, 210 may besaid to provide a biconcave leading edge. The central portion 214 mayinclude a connecting feature 216 that extends outward from the body 203.The connecting feature 216 may be a snap hook to prevent axialseparation, a taper connection to prevent axial rotation and separationwith a friction fit, a connecting feature that allows translation alongthe length of the first component 202, or a cap or clip to maintain theconnection. In the illustrated example, the connecting feature 216includes prongs which extend longitudinally from the body 203. Eachprong may include a lip extending radially from the prongs, wherein eachlip may provide a snap fit or other reversible fixation with the secondcomponent 204. The first component shown in FIGS. 4-5 may be describedas a male staple.

Referring to FIGS. 6-7, the second component 204 also includes a body217, a first arm 218 that terminates in a third blade 220, and a secondarm 222 that terminates in a fourth blade 224, the second arm 222opposite the first arm 218. While an orthogonal arrangement is shown,all other angular relationships between at least the arms and blades arecontemplated. The second component 204 also includes a central portion226, located between the first arm 218 and the second arm 222, which maybe an aperture, receptacle, or socket shaped to receive the connectingfeature 216 of the male connection staple. The first and second arms218, 222 may be said to extend radially from the central portion 226.The first and second arms 218, 222 may have concave leading edges 234and blunt trailing ends 236. Together, the first and second arms 206,210 may be said to provide a biconcave leading edge. The secondcomponent 204 shown in FIGS. 6-7 may be described as a female staple.

When the connecting feature 216 engages the central portion 226 of thefemale connection staple 204, the male connection staple 202 and thefemale connection staple 204 become joined or coupled together such thatthe first blade 210, the second blade 212, the third blade 220 and thefourth blade 222 may extend outward from the connected, aligned centralportions 214, 226 to engage the carpal bones such that the staples 202,204 may become axially fixed, rotationally fixed, or both.

Each of the blades 208, 212, 220, 224 may be angled or contain at leastone angled surface to provide enhanced compression between opposingbones. For example, a blade may be angled so that a tapered leadingpoint of the blade is farther from the corresponding body than atrailing rear portion of the blade, so that as the blade penetrates thebone, the bone is urged toward the body. In an arrangement where everyblade is so angled, each blade may urge a separate bone or bone fragmenttoward the body. Each of the blades 208, 212, 220, 224 may also includeadditional fixation features 228 such as teeth, serrations, or barbs toenhance their interaction with the bones, such as to inhibit backwardmigration of the blade out of the bone after implantation. Theconnection between the female connection staple 204 and the maleconnection staple 202 may not constrain all degrees of freedom, as thecarpal bones may provide sufficient rotational constraint once thefusion device is implanted.

FIGS. 8 and 9 illustrate a fusion device 250 with at least two blades254, 256, and no connecting feature. Fusion device, or staple 250includes a central portion 252 and two lateral blades 254, 256. Thecentral portion 252 may have a sharpened biconcave leading edge 253 anda blunt trailing end 255. The blades may have features similar to thosepreviously described, and may contain an exterior surface 258 that facesaway from the central portion and an interior surface 260 opposite theexterior surface 258. The interior surface 260 may be sloped and mayintersect that exterior surface 258 at a tip portion 262. The orthogonalarrangement shown is one example of the range of all angularrelationships which are contemplated in the scope of this disclosure.

In operation, a first compression staple may be placed proximal to andcrossing a second compression staple. The slope of the interior surfaces260 may create a wedge effect to create compression and achieve thedesired orientation for fusion applications.

It should be understood that the present components, systems, kits,apparatuses, and methods are not intended to be limited to theparticular forms disclosed. Rather, they are intended to include allmodifications, equivalents, and alternatives falling within the scope ofthe claims. They are further intended to include embodiments which maybe formed by combining features from the disclosed embodiments, andvariants thereof.

The claims are not to be interpreted as including means-plus- orstep-plus-function limitations, unless such a limitation is explicitlyrecited in a given claim using the phrase(s) “means for” or “step for,”respectively.

The term “coupled” is defined as connected, although not necessarilydirectly, and not necessarily mechanically.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more” or “at leastone.” The term “about” means, in general, the stated value plus or minus5%. The use of the term “or” in the claims is used to mean “and/or”unless explicitly indicated to refer to alternatives only or thealternative are mutually exclusive, although the disclosure supports adefinition that refers to only alternatives and “and/or.”

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, a method ordevice that “comprises,” “has,” “includes” or “contains” one or moresteps or elements, possesses those one or more steps or elements, but isnot limited to possessing only those one or more elements. Likewise, astep of a method or an element of a device that “comprises,” “has,”“includes” or “contains” one or more features, possesses those one ormore features, but is not limited to possessing only those one or morefeatures. Furthermore, a device or structure that is configured in acertain way is configured in at least that way, but may also beconfigured in ways that are not listed.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. It isappreciated that various features of the above-described examples can bemixed and matched to form a variety of other alternatives. For example,a blade configuration from one or more fixation device examples may befound on the other fixation device examples disclosed herein. Similarly,manufacturing, assembly or implantation methods described for onefixation device or component may be used in the manufacture, assembly orimplantation of the other fixation devices or components disclosedherein. As such, the described embodiments are to be considered in allrespects only as illustrative and not restrictive. The scope of theinvention is, therefore, indicated by the appended claims rather than bythe foregoing description. All changes which come within the meaning andrange of equivalency of the claims are to be embraced within theirscope.

The invention claimed is:
 1. A fusion device comprising: a firstcomponent comprising a first body, a first arm, a first blade, and aprotruding connecting feature, wherein the first arm comprises a concavefirst leading edge and a blunt first trailing end, wherein the first armextends outward from the first body and terminates in the first blade,wherein the first blade extends transverse to the first arm, wherein thefirst blade comprises a first sharp tapered point and a first trailingportion opposite the first sharp tapered point, wherein the protrudingconnecting feature protrudes from the first body; and a second componentcomprising a second body, a second arm, a second blade, and areceptacle, wherein the second arm comprises a concave second leadingedge and a blunt second trailing end, wherein the second arm extendsoutward from the second body and terminates in the second blade, whereinthe second blade extends transverse to the second arm, wherein thesecond blade comprises a second sharp tapered point and a secondtrailing portion opposite the second sharp tapered point, wherein thereceptacle is recessed within the second body; wherein when the firstand second components are coupled together, the protruding connectingfeature is received in the receptacle, the first and second bodies arealigned, the first leading edge, the first tapered point, the secondleading edge, and the second tapered point all face the same way, thefirst and second tapered points diverge outward from the first body, andthe first and second trailing portions converge toward the first body.2. The device of claim 1, wherein the second arm is longer than thefirst arm.
 3. The device of claim 1, wherein the protruding connectionfeature comprises prongs extending longitudinally from the first body.4. The device of claim 1, wherein the second component rotates relativeto the first component.
 5. The device of claim 4, wherein the protrudingconnecting feature rotates within the receptacle.
 6. A fusion devicecomprising: a first component comprising a first body, a first arm, afirst blade, and a protruding connecting feature, wherein the first armcomprises a concave first leading edge and a blunt first trailing end,wherein the first arm extends outward from the first body and terminatesin the first blade, wherein the first blade extends transverse to thefirst arm, wherein the first blade comprises a first sharp tapered pointand a first trailing portion opposite the first sharp tapered point,wherein the protruding connecting feature protrudes from the first body;and a second component comprising a second body, a second arm, a secondblade, and a receptacle, wherein the second arm comprises a concavesecond leading edge and a blunt second trailing end, wherein the secondarm extends outward from the second body and terminates in the secondblade, wherein the second blade extends transverse to the second arm,wherein the second blade comprises a second sharp tapered point and asecond trailing portion opposite the second sharp tapered point, whereinthe receptacle is recessed within the second body; wherein when thefirst and second components are coupled together, the protrudingconnecting feature is received in the receptacle, and the first andsecond bodies are aligned.
 7. The device of claim 6, wherein the firstblade comprises a first tapered point and a first trailing portionopposite the first tapered point, wherein the second blade comprises asecond tapered point and a second trailing portion opposite the secondtapered point, wherein when the first and second components are coupledtogether, the first leading edge, the first sharp tapered point, thesecond leading edge, and the second sharp tapered point all face thesame way, the first and second sharp tapered points diverge outward fromthe first body, and the first and second trailing portions convergetoward the first body.
 8. The device of claim 6, wherein the second armis longer than the first arm.
 9. The device of claim 6, wherein theprotruding connection feature comprises prongs extending longitudinallyfrom the first body.
 10. The device of claim 6, wherein the secondcomponent rotates relative to the first component.
 11. The device ofclaim 10, wherein the protruding connecting feature rotates within thereceptacle.